Adjustable lower limb prosthesis and apparatus and method for the adjustment thereof

ABSTRACT

A lower limb prosthesis as a prosthetic foot and an elongate rod formed substantially of unidirectional long fibers embedded in a thermoplastic matrix, the fibers extending substantially parallel to the length of the rod. An adjustment apparatus for the prosthesis includes a pair of pods which may be clamped to the rod and rotated at controlled angles once the thermoplastic rod has been heated to its deformation temperature.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to lower limb prosthesis. Moreparticularly, the present invention is directed to the adjustment oflower limb prosthesis to suit the ambulatory characteristics of theamputee to which it is to be fitted.

2. Background of the Related Art

Lower limb prosthetic devices are presently comprised of two basicclassifications. One classification, termed exoskeletal prostheticdevices, relates to devices where the vast majority of the vertical loadof the amputee is supported by the shell of the prosthetic appliance.This shell has basically the same exterior shape of the lost limb, andis usually manufactured from a combination of wood and rigid thermosetplastics reinforced with some type of long fiber, to which a separateplastic foot may be attached. This construction renders the prosthesishard to the touch, but it may be coated with a thin layer of flexiblematerial for cosmetic reasons.

The second type of lower limb prosthetic appliance is termedendoskeletal. This classification relates to a device which carries thevast majority of the vertical load through an inner supporting member.This inner member, or framework, has a shape totally unrelated to thatof the missing limb. This inner structure is subsequently covered with alight weight flexible foam, which is then given the proper shape. Thisstructure may or may not include an attached prosthetic foot. If aprosthetic foot is not included in the basic design, a separateprosthetic foot is attached.

An AK (above knee) prosthetic appliance most always includes a kneejoint, which is the axis about which the shin portion of the prosthesisrotates. A BK (below knee) prosthesis would usually not contain thisknee joint, and would be used in cases in which the length of theresidual limb is sufficient to support a prosthetic appliance.

A below knee (BK) endoskeletal prosthesis can further be divided intotwo smaller classifications. As of this date, they are not specificallynamed, but can be described as follows. The more popular prostheticdevice, which is accepted as the worldwide standard, is comprised ofseparate foot and shin members, which may be fabricated from componentsof different manufacturers due to modular design features that exist inmuch of the componentry available today. This appliance consists of arigid rod or tube made of metal or thermoset composite material (withthe reinforcing fiber always being glass or carbon) attached to a customfabricated cup or socket which contains the residual limb. At the otheror lower end of this rigid structural tube is the prosthetic foot.

Walking is a complex movement which involves not only the pivoting ofthe lower limb around the knee joint, but also a rotation of the lowerlimb about its length. It is also necessary to obtain an optimalposition of the foot relation to the prosthetic socket using the "trialand error" approach. For this reason, lower limbs are not perfectlystraight but are slightly bent and twisted by amounts unique to a givenindividual. It is therefore common practice to provide lower limbprostheses with angular adjustments tailored to the comfort and gait ofthe individual wearer. For this purpose, before receiving a permanentprosthesis the amputee is given a "temporary leg." This is a somewhatcumbersome device containing many adjustable features to help determinethe proper alignment for the amputee. After a sufficient amount of timewalking on the temporary leg, the prosthetist is able to determine theproper relationship between the prosthetic foot and the socket of theresidual limb. This temporary leg is then placed in an apparatus calleda bench mounted alignment fixture, a device common to the industry. Thesocket, which can be reused, is positioned and held firmly by thisdevice and the position of the foot relative to this socket is thennoted and recorded. The temporary leg, with the exception of the socket,is removed from the bench mounted alignment fixture, making the socketready for the installation of a permanent prosthesis.

The conventional permanent prostheses all use angularly adjustableadaptors at the ends of a rigid rod. An example may be found in Britishpatent specification No. 978,586 which uses a pair of lockable balljoints at the ends of a tube and connecting the tube to both theprosthetic foot and the socket. Although such adaptors (e.g., balljoints) give the prosthesis the advantage of adjustability, they havetwo pronounced disadvantages. They add weight and allow the possibilityof failure due to the mechanical fasteners they contain becomingloosened during normal usage.

Additionally, in order to allow limited rotation about an axis parallelto the length of the tube, a separate device for rotation should beadded. However, such a rotator, although it is highly desirable since itreduces the frictional forces generated between the residual limb andthe socket, is seldom used because of the resulting additional weight.Additional weight increases the swinging mass of the leg and requiresadditional force to maintain the prosthesis firmly attached to theresidual limb. Such additional force almost always irritates scar tissuein the area of the amputation and/or further restricts the flow of bloodto the most critical areas.

An additional shortcoming of conventional lower leg prostheses is theundesirable transmission of vibrations from the foot, through the tubeor rod of the prosthesis, and to the residual limb.

The second or hybrid classification of existing BK prosthesis is thatshown in U.S. Pat. No. 4,865,612, which contains a shank and footconstructed of one continuous member. In this case, the supporting innermember is not a tube but is of a solid, flat rectangular cross section,the wider portion running side to side. This single member designcontinues with a smooth radius in the area of the ankle and out to thetoes. The material from which it is manufactured is basically acombination of carbon and fiberglass fibers, the majority of which runin the direction from prosthesis socket to prosthetic toe, contained ina thermoset epoxy matrix. This renders the prosthesis relatively rigid,but does allow bending under load. This bending under load takes fulladvantage of the composite materials by storing the energy input to thesystem due to the bending forces, and returning it at a later point inthe gait of the amputee. Such energy storage and release is advantageousto more active amputees such as joggers and other sports enthusiasts,but is of little assistance and possibly even detrimental to themajority of amputees. The ability of this construction to allowsufficient rotation about the vertical axis is also extremely limited.This is primarily due to the cross section area being rectangular inshape, the dimensions of this cross section, the orientation of fiberdirections, and the rigid thermoset matrix that bonds the fiberstogether. Alignment changes are also extremely difficult and expensive.Moreover, an added attribute is the composite's high strength to weightratio, resulting in a relatively lightweight prosthesis. The importanceto the amputee of this weight reduction over conventional prostheticappliance construction cannot be underestimated.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a prosthetic lowerlimb and method and apparatus for adjusting the same which allowsadjustment at any point in the useful life of the limb without majormodifications.

It is a further object of the present invention to provide a lower limbprosthesis which is notably lighter in weight than conventionalprostheses.

It is a further object of the present invention to provide a lower limbprosthesis providing limited rotation about an axis parallel to the rodthereof, thereby reducing torque forces between the socket and theresidual limb.

It is a further object of the present invention to provide a lower limbprosthesis which minimizes the number of fasteners which can becomeloose.

It is yet a further object of the present invention to provide anapparatus for adjusting a lower limb prosthesis which is formed ofcomponents which can be readily replaced if necessary.

The above, and other, objects are achieved according to the presentinvention by a lower limb prosthesis comprising a prosthetic foot and anelongate rod having one end fixed to the foot and a proximal end, theelongate rod being formed substantially of unidirectional long fibersembedded in a thermoplastic matrix, the fibers extending substantiallyparallel to the length of the rod.

According to a further feature of the invention, a lower leg prosthesisadjustment apparatus for the lower limb prosthesis includes means forheating the rod to a temperature such that the matrix isthermoplastically deformable and means for deforming the rod about atleast one axis, whereby the rod may be heated and bent for adjustment ofthe prosthesis.

According to a further feature of the invention, a method for adjustingthe lower limb prosthesis includes the steps of heating the rod to atemperature such that the matrix is thermoplastically deformable,deforming the heated rod about one axis, and permitting the deformed rodto cool.

According to a further feature of the invention, there is provided agripping pod for use with the lower leg prosthesis adjustment apparatusfor adjusting the lower limb prosthesis, the gripping pod including abody defining an axis and having a semi-spherical surface centered onthe axis, an axial extension of the body having external cam surfaces,and an axial bore extending through the body and the extension.

Since the invention provides adjustability for the lower limb prosthesisby heating the support rod formed with a thermoplastic resin to atemperature at which the thermoplastic resin softens, and providingadjustment by bending the support rod, there is no need for a permanentadjustment mechanism which can become loosened and which adds weight tothe prosthesis. Additionally, the support rod having a thermoplasticresin is able to damp vibrations from reaching the socket. Additionally,the support rod has unidirectional long fibers extending substantiallyparallel to the length of the rod. This permits the support rod to actas a torsional spring and provide limited and controlled rotation of theprosthetic foot relative to the socket during ambulation of the wearer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an embodiment of the assembled lower legprosthesis adjustment apparatus;

FIG. 2A is a top view of an upper pod of the apparatus of FIG. 1;

FIG. 2B is a sectional view along line 2B--2B in FIG. 2A;

FIG. 2C is a bottom view of the pod of FIG. 2A;

FIG. 3A is bottom view of the lower pod of the apparatus of FIG. 1;

FIG. 3B is a top view of the pod of FIG. 3A;

FIG. 3C is a sectional view taken along line 3C--3C in FIG. 3B;

FIG. 4A is a top plan view of the lower cylinder element in theapparatus of FIG. 1;

FIG. 4B is a section taken along line 4B--4B in FIG. 4A;

FIG. 4C is a front elevation view of the cylinder element of FIG. 4A;

FIG. 5A is a top plan view of an upper cylinder element in the apparatusof FIG. 1;

FIG. 5B is a sectional view taken along line 5B--5B in FIG. 5A;

FIG. 6 is a side elevation view of the socket adaptor in the apparatusof FIG. 1;

FIG. 7 shows the BK prosthesis prior to application of the prosthesisadjustment apparatus; and

FIG. 8 is a circuit diagram of the heater control system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following, non-limiting, example, the same reference numeralswill be used to reference the same or corresponding parts throughout theseveral views.

Referring to FIG. 7, a BK endoskeletal prosthesis according to thepresent invention is shown. It comprises two main elements, a footprosthesis 2 and a lower limb prosthesis 4. The foot prosthesis 2 can bethat according to U.S. Pat. No. 4,865,612. For a detailed illustrationof the preferred foot prosthesis, reference can be had to that patent.The lower limb prosthesis 4 comprises a solid straight rod having alower end fixed to the foot prosthesis 2, and having an oppositeproximal end 6. The diameter of the rod 4 is selected by the prosthetistwho is to assemble the prosthesis. This diameter will be selected from 2to 4 standard sizes. A larger diameter is required for heavier amputeesand also for those amputees who may demonstrate a very active lifestyle.A smaller diameter would be applicable to light weight amputees oramputees exhibiting a limited activity level. The rod 4 is constructedof unidirectional fibers embedded in a thermoplastic matrix. Thepredominant direction of the fiber placement is as near parallel withthe axis of the rod as is possible. This configuration permitsresistance to vertical loads applied by the amputee in normal usage,while absorbing limited torsional stresses about the longitudinal axisof the rod, to thereby absorb torsional loads arising during walking,i.e., limited rotation of the socket relative to the prosthetic foot ispossible during ambulation. This significantly reduces abrasion to theskin on the residual limb of the amputee. Further, the ability of thethermoplastic of which the matrix is composed to absorb shocks anddampen vibrations transmitted from the foot to the socket is realized.

The preferred thermoplastic matrix of the fiber/matrix system is nylon6, due to its high impact resistance, low melting point, and relativelyhigh tensile strength and fatigue resistance. Other matrices such asnylon 6/6, nylon 12, glycol modified polyethylene terapethalate (PET-G),and low molecular weight nylon 6 could also be used effectively. Thepreferred fiber reinforcing material is carbon or graphite fibers due totheir stiffness, their high strength to weight ratio, and their highcoefficient of thermal conductivity. Fiberglass reinforcing fibers,polyethylene based Spectra fibers (Allied Chemical), Kevlar 49 or 149(Dupont) and others may be substituted. The tensile modulus (17,000,000to 30,000,000 psi) and high ultimate strength (up to 700,000 psi) of thecarbon fibers, coupled with the unidirectional configuration, permit thecompleted prosthesis to adequately resist vertical loads with onlyminimal resistance to torsion.

As earlier discussed, the rod 4 is constructed principally of carbonunidirectional fibers in a nylon matrix. In this construction, it isimperative that the carbon fibers remain as long as possible and asstraight as possible. This dictates that either compression orpultrusion molding techniques of continuous or near continuous fibers beutilized. Since the distal end of the rod 4 requires a particular shapeother than that of the normal cross section, this requires eithercompression molding be employed (the preferred method) or pultrusion andsubsequent post-forming of the distal end of the rod (alternativemethod). Conventional injection molding is inadequate in that extremelyshort fiber lengths (approximately 3/8 to 1/2 inches) result. Thisdrastically reduces the mechanical properties along the axis of the rod,which necessitates an increase in the diameter and thereby increases thetorsional resistance due to the composite becoming more isotropic,resulting in an increase in the frictional forces at the socket/residuallimb interface.

The proximal end 6 of the prosthesis is attached to a conventionalsocket (not shown) via an adaptor 8 (FIG. 6) which is fixed to theproximal end 6 of the prosthesis. However, before the prosthesis can beproperly worn, it is necessary to adjust the prosthesis to the gait ofthe wearer by adjusting the angular relationship between the prostheticfoot 2 and the socket of the residual limb, using adjustment criteriadetermined by the prosthetist based upon adjustments made to thetemporary leg.

According to the present invention, rather than providing adaptors foradjusting the prosthesis, the rod 4 is bent about axes transverse to itslength, at two positions along its length. This is done by adjustment ofthe apparatus 1 shown in FIGS. 1-5 and 8.

Referring to FIG. 1, the adjustment apparatus 1 has the following maincomponents: An upper pod 10 is clamped to the proximal end of the rod 4at a position surrounding the lower portion 40 of the adaptor 8. A lowerpod 12 is clamped to the lower end of the rod 4. Between the pods 10 and12 extends an adjustable cylinder 14, whose length is adjustable in theaxial direction. The cylinder 14 is in fact composed of a lower cylinderelement 16 and an upper cylinder element 18. The lower and uppercylinder elements are connected to one another in an axially adjustablemanner, for example by meshing threads 20 and 22 at the joined ends ofthe cylinder elements.

A silicone sleeve or cover 24 surrounds the portion of the rod betweenthe pods 10 and 12, and at least a part of the length of the siliconecover is in turn covered by a heating means, such as a flexibleresistance heating coil 26 wound around the sleeve 24. The coil 26 heatsthe rod 4 when it is energized by electrical current via the controlunit 28. The control unit 28 receives temperature signals from a coretemperature sensor 30 and a surface temperature sensor 32.

Referring to FIGS. 2A through 2C, the upper pod 10 is formed of twosubstantially symmetrical halves 10a and 10b which are divided along amedian plane 10c. The pod is formed of metal or rigid plastic,preferably of aluminum, as are the pod 12 and the cylinder elements 16and 18. It defines a central bore 36 which is bisected by the plane 10c.The central bore 36 has a main portion which is shaped to accommodatethe lower portion 40 of the adaptor 8, and a lower portion 42 which istapered outwardly in a direction from the main portion towards thebottom of the bore.

The peripheral surface of the main body of the upper pod 10 takes theform of a semi-spherical surface 44 truncated by a planar top surface 46which may have a bevel 48 at its boundary with the semi-sphericalsurface 44. The semi-spherical surface 44 is centered at point O whichlies on the plane 10c and substantially coincides with one of the axesof bending of the rod 4, as will be explained later. An annular skirt 50depends from the lower part of the semi-spherical surface 44 and forms aunitary extension of the upper pod. This skirt 50 surrounds and definesthe lower portion 42 of the bore.

The skirt 50 exteriorly defines a plurality of cam surfaces 49; 4 in thepreferred embodiment. Each of these cam surfaces 49 is slightly convexand tapers outwardly towards its distal end. In the preferredembodiment, adjacent cam surfaces are angularly separated byapproximately 90°. It may be appreciated that more or fewer than 4 suchcam surfaces may be provided.

The two halves 10a and 10b of the upper pod 10 may be placed around theproximal end of the rod 4 and clamped firmly thereon by bolts whichextend through apertures 51 of the pod half 10b and which are threadedinto aligned threaded holes (not shown) of the pod half 10a. Pods havingbores 36 of diameters corresponding to the diameters of the selectedrods 4 may be used.

The lower pod 12 shown in FIGS. 3A through 3C is similar to the upperpod 10. It is also composed of two symmetrical halves 12a and 12b whichmay be clamped together by bolts (not shown) inserted in holes 52 of oneof the pod halves. It also has a semi-spherical peripheral surface 54centered on point O'. The spherical surface is truncated by a planarbottom surface 56, optionally through the intermediary of a shortcylindrical surface 58. A bore 60 extends through the lower pod and isbisected by the separating plane 12c of the two pod halves. A dependingskirt 64 defines the outwardly tapered upper portion 66 of the bore 60.The outer periphery of the skirt 64 defines, in the illustratedembodiment, 4 convex cam surfaces 68. The key hole 70 engages anoptional key or some other aligning element at the base of the rod 4 forsetting the rotational position of the lower pod 12.

Referring to FIGS. 4A through 4C, the lower cylinder element 16 has abevelled lower inner edge 72 which is intended to bear against thesemi-spherical surface 54 of the lower pod 12. A portion of theperiphery of the lower cylinder is thickened to form an axiallyextending flange 74, through which is partially cut a gap 76 having awidened base 78. A bolt 80 clamps the portions of the flange 74 onopposite sides of the gap 76, near the top thereof, in order to clamponto the upper cylinder element, as will be described below.

Four equally spaced threaded holes 82 are formed in an optionallythickened lower portion of the lower cylinder element 16. These holes 82extend substantially radially but preferably do not extend transverse tothe axis of the cylinder. They are instead slightly angled from a planetransverse to the cylinder axis by the same angle as the outwardtapering of the skirt 64, for example by 16 degrees. Adjusting elements84 (FIG. 1) in the form of threaded rods are threaded into each of theholes 82 until they abut one of the cam surfaces 68.

Referring to FIGS. 5A and 5B, the upper cylinder element issubstantially identical to the lower cylinder element, except that ithas the screw threads 22 on the outer periphery thereof and lacks theflange and gap. It has an annular bevel 86 in its top end, and also hasthreaded holes 88 for adjusting elements 84. The threaded holes 88extend radially and are angled with respect to a plane transverse to thecylinder axis by an angle which preferably equals the taper angle of theskirt 50, e.g., 16 degrees.

The elements are assembled in preparation for an adjusting operation, asfollows:

First, the silicone sleeve 24 is placed around the rod 4. The siliconesleeve is intended to help maintain the shape of the soft thermoplasticof the rod 4 when it is heated. The interior cross section of thesilicone sleeve 24 should be slightly smaller than the exterior crosssection of the rod 4, so that the silicone sleeve compresses the rod.The silicone sleeve may be fiber reinforced for increased strengthand/or to help produce the desired shape.

Prior to assembly, a bore hole 4a has been bored into the rod 4 by adistance sufficient so that the core sensor 30 can be inserted thereinand sense the core temperature of the rod 4. The sleeve 24 is positionedover the core sensor 30. To do this a hole is bored in the sleeve andthe core sensor is inserted into the bore hole 4a through the hole inthe sleeve. The surface temperature sensor 32 is mounted on the sleeveitself. Each of the temperature sensors 30 and 32 can be a thermocouplesensor of a conventional type.

Subsequently, the heater coil 26 is wound around the sleeve 24 and thelower pod 12 is clamped onto the lower portion of the rod 4 to tightlygrip the rod 4, the lower cylinder element 16 is laid on the lower pod12, and upper cylinder element 18 of a desired length is selected andthreaded into the lower cylinder element. The lead wires of the heatingcoil and the temperature sensors are extended through the gap 76 priorto attachment of the upper cylinder element. The adaptor 8 is lightlyclamped onto the proximal end of the rod 4 by the adaptor bolt 8a, andthe upper pod 10 is clamped onto the distal end of the rod 4 over thelower portion 40 of the adaptor 8. The upper cylinder element is thenrotated until the bevelled ends of the cylinder elements 16 and 18tightly abut the semi-spherical surfaces of the pods. At this time, thebolt 80 is tightened so as to lock the axial length of the cylinder 14.The adjusting elements 84 are then adjusted to abut the cam surfaces, sothat the positions of the pods 10 and 12 are stabilized. It should benoted that the adaptor 8 only lightly grips the rod 4 and can slidethereon. The upper pod 10 is clamped on the adaptor 8 and so also onlylightly grip the rod 4, which permits necessary sliding of the upper podon the rod during an adjustment procedure.

For the adjustment operation, heater is turned on, whereby thecontroller 28 causes a current of approximately 3-4 amps to flow throughthe flexible coil 26 for a set time such as approximately six minutes(or a shorter time, as described below). This is the optimal time withthe smallest (18 mm) diameter rod. Heating time will increase as largerdiameter rods are utilized. During heating of the rod, two criteria mustbe controlled. Heating must be sufficient for the core of the rod toreach a softening temperature, typically approximately 420° F. However,the outer surface of the rod must be maintained below a maximumtemperature of about 550° F.; higher temperatures can result inuncontrolled flow of the softened matrix and damage of the siliconesleeve will occur.

Once the rod 4 has reached its softening temperature, it can bethermoplastically deformed by adjustment of the adjusting elements 84.Thus, by adjusting two radially opposed elements 84 on the upper pod 10,one can deform the proximal end of the rod 4 about an axis lyingsubstantially on the center point O and directed transverse to the axisof the rod 4. Adjustment of the other two opposing adjustment elements84 abutting the upper pod 10 causes deformation of the proximal end ofthe rod 4 by pivoting about an axis which also lies substantially on thecenter point O, extends transverse to the longitudinal axis of the rod4, and is transverse to the earlier mentioned bending axis. Adjustmentis performed to set the bending angle to a value determined byadjustment of the temporary leg. A similar procedure is carried out forthe lower pod 16.

Once the above procedure is completed and the rod has cooled, the mobilealignment fixture is removed by an assembly sequence opposite to thatset forth above.

Any heater control can be used which is capable of sensing the core andsurface temperatures and heating the rod while preventing overheating. Apreferred control 28 is schematically shown in FIG. 8. It includes atemperature controller 100, which may be the SHIMADEN Model SR34, whichcontrols the current to the heater 26 via a solid state relay 102, whichis preferably the CRYDOM Model D2410. The temperature controller 100 isa set point type controller which thermostatically limits current to theheat element 26 when the surface sensor 32 detects the surfacetemperature higher than that set for the controller (e.g. 550° F.). Thecore temperature controller 104 is preferably the SHIMADEN Model SR32,and emits signals to an alarm 106 and an indicator light 108, via arelay 110 when the core temperature sensor 30 senses that the melt pointor deflection point temperature of the thermoplastic material has beenreached. Current to the alarm can then be shut off via the button switch112. Although not shown, the core temperature controller 104 shouldcontinuously display the core temperature. Optionally, the alarm 110 canbe made to notify the user when the temperature has reached a pointbeyond which the thermoplastic material may begin to degrade, or someother relevant point.

The switch 114 is included to energize the other components, while aninterval timer 116 is set to limit the maximum time that thethermoplastic part can be heated during each shaping session, e.g., 45minutes. This is especially important for materials which tend todegrade when exposed to elevated temperatures for extended periods oftime. Also provided are fuses 118, 120 and 121, as well as a groundfault circuit interrupter (not shown). Ground is shown at 122.

If the alignment procedure is not satisfactory, the fixture can bereinstalled in the manner set forth above and the heating cyclerepeated.

The total weight of an average BK prosthesis according to the presentinvention is approximately 15-35% lighter than one manufactured byconventional techniques. This is primarily due to the compositematerials used and the elimination of the additional weight resultingfrom torque absorbers and adaptors. A very significant savings in labormay also be demonstrated. The prosthesis is subsequently completed usingconventional endoskeletal techniques of shaping and installing of asoft, flexible foam cover which is placed over the tubing.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by letters patent ofthe United States is:
 1. A lower leg prosthesis adjustment apparatus foradjusting a lower limb prosthesis including a prosthetic foot and anelongate rod having one end fixed to the foot and a proximal end, theelongate rod being formed substantially of unidirectional long fibersembedded in a thermoplastic matrix and extending substantially parallelto the length of the rod, said apparatus comprising:means for heatingthe rod to a temperature such that the matrix is thermoplasticallydeformable; and means for deforming the rod about at least one axis,whereby the rod may be heated and bent for adjustment of the prosthesis.2. The apparatus of claim 1, wherein said means for deforming comprisemeans for deforming the rod about at least two spaced axes perpendicularto the length of the rod.
 3. The apparatus of claim 2, wherein saidmeans for deforming the rod comprise:means for gripping the rod at twoportions on the length of the rod; and means for pivoting the grippingmeans about said axes.
 4. The apparatus of claim 3, wherein saidgripping means comprise two pods, each of said pods having a portionfittable on the rod for gripping the rod, each said pod having at leastone cam surface spaced from the gripping portion in the direction of thelength of the rod when the pod is fitted on the rod.
 5. The apparatus ofclaim 4, wherein said pivoting means comprise:a frame mountable on theprosthesis and between said pods so as to be stationary relative to therod; and adjustment elements mounted on said frame and engagable withsaid at least one cam surface of each said pod for pivoting said atleast one cam surface, whereby adjustment of said adjustment elementspivots said pods about said axes perpendicular to the length of the rod.6. The apparatus of claim 5, wherein said frame comprises a cylinder,wherein said pods each have semi-spherical surface fitted in an end ofsaid cylinder, so that said pods each pivot about the center of saidsemi-spherical surface and wherein said cylinder is mountable on theprosthesis via said pods being fitted on the rod.
 7. The apparatus ofclaim 6, wherein said adjustment elements comprise screws threaded insaid cylinder and abutting said cam surfaces.
 8. The apparatus of claim6, wherein said cylinder comprises two cylinder elements axiallyadjustably fitted to one another, whereby said spherical surfaces ofsaid pods may be tightly abutted to the ends of said cylinder.
 9. Theapparatus of claim 6, including a socket adapter fittable in one of saidpods, and means on said socket adaptor for fixing said socket adaptor tothe rod.
 10. The apparatus of claim 1, wherein said heating meanscomprise a thermostatically controlled electrical heating coil woundaround the rod.
 11. The apparatus of claim 10, including a hightemperature silicone sleeve fittable between the rod and said heatingcoil.
 12. The apparatus of claim 10, wherein said heating means includea controller sensitive to a core temperature of the rod and a surfacetemperature of the rod, said controller including means forthermostatically limiting a maximum surface temperature of the rod. 13.A method for adjusting a lower limb prosthesis including a prostheticfoot and an elongate rod having one end fixed to the foot and a proximalend, the elongate rod being formed substantially of unidirectional longfibers embedded in a thermoplastic matrix and extending substantiallyparallel to the length of the rod, comprising the steps of:heating therod to a temperature such that the matrix is thermoplasticallydeformable; deforming the heated rod about at least one axis; andpermitting the deformed rod to cool.
 14. The method of claim 13, whereinsaid deforming step comprises:positioning around said rod a cylinderhaving gripping pods abutting opposite ends of the cylinder, the podsgripping the ends of the rod, and pivoting at least one of the pods to adesired adjustment angle relative to the cylinder.
 15. The method ofclaim 14, wherein said heating step comprises fitting a heating coilaround the rod prior to said step of positioning the cylinder around therod; andactivating the heating coil.
 16. The method of claim 15, whereinsaid positioning step comprises adjusting the length of the cylindersuch that pods tightly abut the ends of the cylinder.
 17. The method ofclaim 15, wherein said pivoting step comprises adjusting adjustmentelements fitted in the cylinder and abutting a cam portion of one ofsaid pods.